economy and america's future. he would disagree, he thinks the policies are working. i think the evidence shows they're not. government spending created jobs and opportunity, america would be leading the world in job creation right now. i hope he loses his elections, not because he's a democrat, but because policies are bad for america. >> reporter: a debate he says he will continue to have, but from the united states senate, not the campaign trail. i'm jonathan karl for "nightline" in miami. >> look for jon's full interview on abcnews.com/nightline. thanks to jon for that. >>> and coming up, we turn to the incredible story of a terrible shark attack and the inspiring young surfer girl who left it all in her wake. depression is a serious medical condition. i feel like i have to wind myself up to deal with the sadness, the loss of interest, the lack of energy. [ male announcer ] ask your doctor about pristiq -- a prescription medicine proven to treat depression. pristiq is thought to work by affecting the levels of